title: Oxidized glutathione fermentation using Saccharomyces cerevisiae engineered for glutathione metabolism.
abstract: Glutathione is a valuable tripeptide that is widely used in the pharmaceutical, food, and cosmetic industries. Intracellular glutathione exists in two forms, reduced glutathione (GSH) and oxidized glutathione (GSSG). Most of the glutathione produced by fermentation using yeast is in the GSH form because intracellular GSH concentration is higher than GSSG concentration. However, the stability of GSSG is higher than GSH, which makes GSSG more advantageous for industrial production and storage after extraction. In this study, an oxidized glutathione fermentation method using Saccharomyces cerevisiae was developed by following three metabolic engineering steps. First, over-expression of the glutathione peroxidase 3 (GPX3) gene increased the GSSG content better than over-expression of other identified peroxidase (GPX1 or GPX2) genes. Second, the increase in GSSG brought about by GPX3 over-expression was enhanced by the over-expression of the GSH1/GSH2 genes because of an increase in the total glutathione (GSH + GSSG) content. Finally, after deleting the glutathione reductase (GLR1) gene, the resulting GPX3/GSH1/GSH2 over-expressing ΔGLR1 strain yielded 7.3-fold more GSSG compared with the parental strain without a decrease in cell growth. Furthermore, use of this strain also resulted in an enhancement of up to 1.6-fold of the total glutathione content compared with the GSH1/GSH2 over-expressing strain. These results indicate that the increase in the oxidized glutathione content helps to improve the stability and total productivity of glutathione.
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kiriyama
authors.forename: Kiyotaka Y
authors.initials: KY
authors.lastname: Hara
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D001709:Biotechnology / Q000379:methods; D005285:Fermentation; D017353:Gene Deletion; D015870:Gene Expression; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D005981:Glutathione Synthase / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C508746:GLR1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005979:Glutathione Peroxidase; C494438:HYR1 protein, S cerevisiae; C490862:GSH1 protein, S cerevisiae; D005721:Glutamate-Cysteine Ligase; D005981:Glutathione Synthase; D019803:Glutathione Disulfide